herbie7

I've been doing my own repairs for over forty years and have done just about anything you could imagine,but these codes have me at my wits end! Here is a kinda of summary of what I have done.
Did all the electrical checks at evp,evr,pcm and all checked out good.
Checked the egr valve and it functions good.
Removed the upper intake and completely cleaned it out.
Checked soup can and it holds vacuum
Checked input vacuum at evr and have 20hg at idle.
replaced hose from output of evr to egr valve.
I went ahead and replaced the evr and evp
Removed the pcm and opened it up to look for anything odd, all looks good.

The 556,558,332 are all KOEO codes
The truck starts,idles and runs good, this stupid CEL will not go out because of the egr circuit.

Okay now to my question, when back probing the voltage at the evr I get 14.06 at idle and as I increase the rpm the voltage drops to as low as 8.86.I have the mulimeter red lead back probed to the evr and the black lead to the negative side of the battery.
Is this voltage drop normal as I increase rpms or not?
Thanks for any help,Jerry

sdmartin65

I'd pull the vacuum harness off and bench test it, I'd bet there is a problem somewhere in the lines.

I run a cam and am at higher elevation so only produce 15hg at idle. I get codes similar to yours. I have a vacuum line running from the manifold tree to the evr, this clears codes. If all else fails this would work.

herbie7

Thank you Martin for the reply, I have checked the vacuum lines and seem to be fine. It seems to me the evr function is quite simple, vacuum in, vacuum out controlled by the pcm. I have vacuum in at 20hg that should be sufficient I would think, Vacuum out was around 5hg, sometimes no vacuum at all ( the engine is at operating temperature). I was thinking may be a pcm failure, not sure. I replaced the wire from pin 33 to the evr so I knew for sure that was okay even though it checked okay.

I am very curious about the fluctuating voltage at the evr. As I increase rpm the voltage drops, this may be normal,I don't know. But would like to know for sure. Thanks,Jerry

herbie7

The more I think about the fluctuating voltage the more I think that's normal. If the evr has full voltage at idle that would close the solenoid and as rpms increase voltage decreases to open the solenoid to allow vacuum to pass through,at least that seems logical to me.And if that is happening the pcm is doing its job correctly, so I guess the only thing left is a vacuum problem like Martin said. Boy I have gone over and over this thing but I'm not giving up,I'll recheck all the vacuum lines again.

I have searched this problem out over the internet for months and came up with a lot of ideas but it seems as though this 332 is happening to several of these trucks.
Jerry

herbie7

I went out this morning to check the vacuum lines again and checked the operation of the egr valve once more. This time there was no movement at all so I checked the voltage at the evr and I still had over 14 volts at idle so I revved it up little by little and no change in voltage, so I think the problem finally reared its ugly head! The pcm must be bad, so off to the salvage yard. I found the exact one I needed for under $30
I just finished installing and test driving the truck and the light is gone,the egr is functioning correctly,then took a code reading and all three codes are gone. I'm getting the 111, Hallelujah!!!!

Hope this helps someone else, Jerry